Intra-Workout Nutrition
In the previous two newsletters we spoke about pre- and post-workout nutrition. Today we are going to discuss intra-workout nutrition. (you can visit AK life for all previous newsletters)
NUTRITION
According to the International Society of Sports Nutrition, the timing of energy intake and the ratio of certain ingested macronutrients may enhance recovery and tissue repair, augment muscle protein synthesis, and improve mood states following high volume or intense exercise.
For exercise sessions that are aerobic or anaerobic and lasting less than 60 minutes, carb and protein intake is not warranted, provided that the athlete is well-fueled pre-workout. However, for sessions lasting over 60 minutes of high intensity (greater than 70% VO2 max), carb and or protein ingestion may be beneficial to optimize performance. ** please note that doing steady state cardio that is lower in intensity, even if it is longer than one hour, is not that same as high intensity bouts.
For aerobic training over 60 minutes which is working above 70% VO2 max, it is recommended to consume 30-60 grams of carbs per hour. Some studies have also shown that combining glucose and fructose can enhance carb absorption beyond 1 gram per minute, however, there isn’t conclusive evidence. There are multiple ways to consume carbs intra-workout, however, easy to digest sources like dextrin consumed at regular intervals of 10-12 minutes have been proven to optimize performance and maintain blood glucose levels.
In terms of resistance training, there is some evidence that consuming a carbohydrate beverage with or without protein can increase muscle glycogen stores, ameliorate muscle damage and facilitate greater training adaptations. Compared to endurance training, there isn’t as much of a decrease in muscle glycogen with resistance training. Ingesting carbs doesn’t necessarily improved performance, rather, it reduces the loss of muscle glycogen by 50%.
Consuming protein in addition to carbs during your sessions can help decrease muscle protein breakdown. Either consuming essential amino acids or a protein supplement like whey that is easy to digest would be optimal to keep blood aminos high and reduce the rate of muscle protein breakdown during exercise sessions.
Examples of easy to digest carbs:
- 1 tbsp Honey = 18 grams
- 1 tbsp Maple syrup = 13 grams
- 1 Date (chewed well) = 18 grams
- 1 cup Coconut Water = 17 grams
- 1 cup Orange Juice = 25 grams
- 1 tbsp highly branched cyclic Dextrin = 15 grams
- 100 grams Banana (small) = 23 gram
International Society of Sports Nutrition Position Stand on Nutrient Timing
https://jissn.biomedcentral.com/articles/10.1186/s12970-017-0189-4
EXERCISE
How Long to Rest between Sets & How Long your Workouts should Last
The amount of time you should rest between sets truly depends on your goals for training. Are you training to increase strength? Are you training for hypertrophic reasons? Are you training to increase muscular endurance?
If you are training for strength, most likely you are doing 1-6 reps during your sets. Whereas hypertrophy training would be in the 6-20 rep range and endurance upwards of 20 reps. Now this is just a guideline, however, studies have shown that 25 reps taken to failure results in muscle protein synthesis, and reps under 6 that focus more on strength can slightly contribute to MPS as well. So please take this as a rough template.
Depending on your goals for that session, your rep range will change, and in turn your rest time will change.
You have three main energy systems in the body; PCr, Glycolytic and Oxidative.
For strength athletes, they are primarily using the PCr system to generate ATP for short duration, high intense bouts lasting under 30 sec. This is typically going for a 1-3 RM. This system takes about 3-5 minutes to resynthesize available ATP.
The glycolytic system breaks down glycogen, and it is the main energy system used for bouts that are greater than 30 sec and less than 2 minutes. Typically, you are working around 60-85% 1 RM. It is best to rest 1-3 minutes between sets for hypertrophy sessions.
For anything longer than 2 minutes, you will be relying on both the glycolytic and oxidative systems. For endurance sets where you do 30 reps, it could take you up to 3 minutes to complete the set. Because it is lighter in intensity, the rest required before the next set decreases. You can rest about 30 seconds before completing the next set and be good to go. The purpose is to increase muscular endurance, not necessarily build muscle or increase strength, therefore, the fatigue is more general fatigue versus muscular fatigue.
Now, to address the question of how long your workout should last, we would want to consider a few things. Firstly, what is your goal? If you are working out for muscular endurance, then this can be anywhere from 30 minutes to 90 minutes. I would be mindful of overtraining, however there is more of a range when it comes to endurance training as it relies more on the oxidative system.
With regards to hypertrophy training, it will depend mostly on your experience level. If you are a beginner, intermediate or advance, that will determine how many sets you need to do for growth. Studies have shown that anywhere from 10-20 sets per muscle group is sufficient for muscle growth. Anything further than 20 sets per week per muscle group is overtraining and can lead to a decline in progress. Typically, it is recommended to do 4-6 sets per session and train the muscle twice a week. For strength, typically you will want to do 5 sets as you are doing less reps per set.
Here is a good paper to read on overtraining:
https://pubmed.ncbi.nlm.nih.gov/9068095/
DID YOU KNOW?
Your liver can store around 80-100 grams of glycogen, whereas skeletal muscle can store around 300-400 grams of glycogen. The more muscle you have, the greater storage capacity you have for muscle glycogen. This in turn can help with blood sugar management.